1. Technical Field
The present invention relates to an infrared detector or other thermal detector, a thermal detecting device, and an electronic instrument.
2. Related Art
A known type of thermal detecting device is a pyroelectric or bolometric infrared detection device. The infrared detection device detects infrared radiation by absorbing heat in the form of infrared radiation with an infrared absorbing film and detecting an electromotive force generated (pyroelectric) or a change of a resistance value (bolometric) in a thermal infrared detection element. The infrared detection element is supported by a support member and a hollow section is formed between the support member and a substrate for thermal isolation.
From the perspective of reducing the amount of heat dissipation from the thermal infrared detection element, a support arm section that connects the support member to the substrate is configured to be narrow and elongated to reduce thermal conductance and decrease heat capacity. However, the support arm will not have sufficient strength if it is too narrow. If the strength is insufficient, then the support member may adhere and become stuck (sticking) to a bottom surface of the hollow section during manufacturing or the orientation of the detection element may change during use and cause a light capturing efficiency to decline.
Therefore, such ideas as configuring the support arm to have a cross-sectional shape that is curved or has chamfered corners in order to relieve stress in the support arm (Japanese Laid-Open Patent Publication No. 2009-31197) or configuring the support arm to have a step-shaped circumferential change or undercut that increases a second moment of inertia of the support arm and thus increases a bending strength of the support arm (Japanese Laid-Open Patent Publication No. 2007-71885).